


Cheer

by CatKing_Catkin



Category: Adventure Time
Genre: "I Know You're In There Somewhere" Fight, Angst with a Happy Ending, Apocalypse, Bonding, Cross-Generational Friendship, Developing Relationship, Emotional Hurt/Comfort, Epic Battles, Friendship, Future Fic, Gen, Goodbyes, Happy Ending, Headcanon, Hurt, Hurt/Comfort, In Medias Res, Injury, Memory Loss, Mind Control, Mind Rape, Nightmares, Possession, Sacrifice, Singing, Speculation, Team Dynamics, Undead, Vampires
Language: English
Status: Completed
Published: 2013-06-10
Updated: 2013-06-10
Packaged: 2017-12-14 14:30:16
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,121
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/837937
Author URL: https://archiveofourown.org/users/CatKing_Catkin/pseuds/CatKing_Catkin
Summary: <blockquote class="userstuff">
              <p>Written for H/C bingo on Dreamwidth, prompt: "apocalypse". Speculative future!fic. </p><p>The Lich returns, and its new host is powerful enough to sweep aside all opposition. All except one. With Ooo dying around her, Marceline faces off against a possessed Ice King. She knows of only one way to save him, and it will be the hardest battle she's ever faced to put her plan into action. All Marceline has left is her voice, raised in song, trying to reach Simon through the Lich's control, as she makes her last stand.</p>
            </blockquote>





	Cheer

**Author's Note:**

> So I'm not too sure how canon this fic is. There's a lot of speculation and inference involved, just because there's a lot we don't know about most of the major players involved here. But I think they're sound inferences, if nothing else. It's a pretty safe bet that Ice King does have moments of lucidity (what "lucidity" means, of course, remains to be seen), and the Lich gets more dangerous and subtle each time he appears. The crown has its own consciousness and history is, if not stronger than the Lich, than almost certainly older, and it's actually quite protective of its host. And Marceline is pretty dang powerful when it comes to a straight fight.

_“Dun da da da da dun dun…”_

Desperate, afraid, heartsick, and outmatched, Marceline transformed. She donned her wolf shape like battle armor, hair growing to shield her from his ice, muscles strengthening to overpower him, teeth growing into razor sharp fangs and fingernails turning to claws.

She kept one paw clenched tight around Ice King’s crown. And she kept singing. Out in the cold, with Ooo dying around her, facing down the most powerful wizard in the land possessed by the greatest evil, her voice and this one last hope were all she had left. 

_“Making your way in the world today takes everything you’ve got.”_

The Ice King didn’t look that different. His skin had been blue for hundreds of years. If it had taken on a sickly, dusty grey tinge, they hadn’t noticed.

He hadn’t even acted that different, until it was almost too late to stop him. His eyes had held the gleam of madness for hundreds of years. Even Marceline, who loved him, knew that the crown could make him cruel. Even at his most well meaning and good intentioned, the Ice King was irreversibly mad.

But now his eyes were pools of black, lit only by noxious green pupils. His laugh was the whisper of the wind through a hollow skeleton, the last gasp of a corpse. Evil had taken hold of him, something even worse than the crown. 

She wouldn’t let it keep him.

 _“Song is pointless,”_ the Lich hissed in his voice. _“Even if you are lifeless, I will see you die.”_

Marceline shook her head. It wasn’t pointless. He’d shown her that. No matter how hard things looked, singing could keep back the darkness just a little longer. And sometimes, a little longer was all you needed. _“Taking a break from all your worries sure would help a lot!”_

She charged at him. He sent his deathly green fire at her in bolts, but she ducked, dodged, and rolled. She didn’t have a sweater to protect her. There was no one left to like her a lot. All she had were her own inhuman reflexes to match his. For the moment, they were enough. She wasn’t sure even she could heal in the face of his power.

Marceline closed with him, and swung the crown at his head. He caught her wrist, and his grip was strong enough to make her cry out at the feeling of her bones grinding. Gritting her teeth, Marceline tossed the crown into the air, kicked herself away from him, and caught it as it came down. He didn’t give her any time to recover, lunging at her with fists raised and fangs bared. Ice glittered on his fingers, turning them into claws. Even without the crown, the secrets of ice and frost were still burned into his brain. The Lich was more than happy to make use of them.

They clashed. The Lich tore at her with claws and fangs and cold. Marceline healed herself just in time to receive a new wound. Finally, she was forced to retaliate in full, raking at him with her nails and biting with her teeth.

She didn’t want to hurt him. She didn’t want to fight him. She didn’t even want to put this crown back on his head, but if there was one thing strong enough to force the Lich’s spirit out of him, it was whatever was inhabiting this glittering gold crown. The fact that he was trying to stop her only made Marceline more certain that it was the right call.

 _“Wouldn’t it be nice to get away…”_  Tears froze on her face. Her blood froze as she bled. Marceline had never even considered the possibility of dying since she’d become a vampire, but in a moment of weakness, she wondered if this might be how she finally went out.

A rush of resolve strengthened her, then, and made her keep fighting on, keep singing. Because if nothing else, she wanted to spare Simon any further torment on her behalf. If nothing else, she wouldn’t let whatever was left of him feel the pain of killing him.

If nothing else, he’d taught her to never give up.

_“…where everybody knows your name!”_

And there was something left. She felt him faltering as she sang. With a scream, Marceline pounced, bearing them both to the crown. Triumphant, she raised the crown, ready to bring it down in its proper place on his head.  

She looked down at him. He looked up at her.

He smiled. _“Do you feel awesome?”_

She felt his power wash over her mind like a tsunami, a last effort to stop her. All of his will, focused on imploring her to do one simple thing.

She heard the commands as Simon’s voice in her head, desperate and afraid, pleading with her: _“Marceline, put down the crown! Please! You don’t understand how evil it is! You don’t understand what it’s done to me, or how it could hurt you! Please, don’t make me wear it again! Don’t make me forget you!”_

For a moment, Marceline faltered. For a moment, she saw not the Ice King, possessed by the Lich. Instead, she saw Simon Petrikov, as she hadn’t seen him for a thousand years – human, and afraid, but always determined to protect her. No matter what it cost him.

The fact that it had cost him his sanity was something that Marceline had never quite come to terms with.

The Lich had nearly taken her out without a fight, just by letting her see him again, as he had been. Even if it had been a trick, it had been a good one. Even if it had only been for the sake of getting close enough to deliver the finishing blow, he’d given her Simon back.

Just for a moment before snatching him away again.

She wanted him to suffer for that. She wanted him to burn for what he was making her do. Even if they could have forced the Lich out of him now, what would have been left would have been too corrupted to survive.

But the magic of the crown could keep him alive.

The Lich was making her ruin Simon again to save him. It was almost too much to bear.

The thought of letting him die was worse. And so, sobbing, Marceline brought the crown down on his head.

_“Where everybody knows your name…”_

The force of the magic slammed into her, knocking Marceline clear across the chamber to slam painfully into the wall of ice. The power of the Lich met the power of the crown in a whirling nightmare of a gale, making the wind scream in the chamber.

Marceline looked up to see Simon caught right in the middle of it.

Green fire burned around him, only to be frozen in ice. The temperature dropped to killing levels, and it was almost bracing after the Lich’s cloying rot. The Lich was stronger than the crown, but the crown had held onto Simon for longer than the Lich had existed.

“He’s _mine!”_ snarled the crown in Simon’s voice.

It had the home field advantage. And so, with one last great push of energy, the Lich was cast out, screaming, into the ether.

Bodiless and enraged, it went for Marceline first. The fact that she was both a demon and a vampire would be of no consequence to it. She still had a soul to be overtaken. Marceline, who had been forced to stay on the edge of the magical battle, felt it coming at her.

Even if she hadn’t been wounded and tired, Marceline knew there was nothing she could do to stop it. Even if she could have seen it, a vampire couldn’t beat a ghost.

_“No!”_

And then Ice King was between them. Fresh from possession, still ravaged by the Lich’s corruption, he’d come to protect her. His arms were outstretched to shield her, and all his power was focused on the Lich to beat it back from her.

 _“You will never terrify a one thousand and forty three year old man and a one thousand and three year old girl again!”_ he yelled defiantly. There and then, he was a primal force of nature with one purpose. The power of ice and frost was older and stronger even than the Lich, and no one knew its secrets better than the Ice King.

With a howl of rage, the Lich nevertheless finally surrendered, and fled the palace. It wasn’t banished, however. It could still go back and resume its attack on Finn and Jake and the kingdoms.

Marceline tried to fly after it, but she wavered a few feet off the ground, the world tilting crazily around her. She felt her human form reasserting itself against her will, as she was too tired to maintain her wolf transformation. Marceline gritted her teeth, making an effort to keep going…but finally, with a sigh of exhaustion, she felt herself plummeting to the ground.

To her dim surprise, she landed on something soft.

“Werk!”

Gunters One to Twenty held her up proudly.

The Ice King didn’t notice their quick thinking, however. He was obviously wrapped up in his own thoughts, as what passed for his mind tried to catch up.

“Oh. Oh, clam balls. Possessed by the Lich. Yeah, that’s not good. He’s bad news. And he got away. Oh, mother.  Yeah…” He looked right past her, towards the exit of the castle. She saw that he was determined…and focused. “Gotta fix this. Gotta go help.” With a fluttering of his beard, he took to the air and started off.

“Simon?” Marceline called weakly, pushing herself up on her makeshift mattress of penguins. He actually looked back at the sound of his name, he _looked_ at her, and then swerved around to land next to her. The Gunters passed her over, and Simon set her on her feet.

Then he hugged her. Exhausted and trying not to cry, Marceline hugged him back.

“You’re going to act weird again,” she whimpered pathetically. “Don’t go.” It was selfish to say, but after the sacrifice she’d just made, Marceline didn’t feel so bad about being selfish.

She knew that, while he had the crown, Simon was always going to go away again. She also knew that separating Simon from the crown was impossible, for his own sake. And Marceline thought she had come to terms with that, just being satisfied with having him around.

That was when she never thought she’d see him again. Not as he’d once been. It wouldn’t last forever, but it was lasting a little while, and if he had to fight, that would make him fade away again all the more quickly.

“I’ve got to, sweetheart,” he said. “While I still can. If I can’t stop him alone, at least I can help. I have to fight to protect you. To protect everyone, all the people I usually hurt.”

“No you don’t!” she sobbed, holding on to him more tightly. His absolutely maddening _maturity_ only made her want to dig in her heels, childish as it was. “You need to stop protecting people! I’m not a little girl anymore, Simon! Now I really can fight! Finn and Jake are tough, and Bubblegum has all her science! I softened him up, so they can beat him! I know they can. You don’t have to go…”

“…I know, Marcy. I know you can fight. I know you’ve gotten so strong. Because you saved me. Now I need to use the chance you gave me. I need to do some good while I still remember how. But you’ve done enough, sweetheart. Just…rest. And stay safe. For me.”

_And I need to save you. But who’s going to save me?_

The words hung between them like icicles poised to fall. Marceline drew the seconds out as long as she dared before she nodded, and stepped away. Immediately, she felt unsteady, like she was trying to fly even though her feet were planted firmly on the ground.

Marceline swallowed painfully. Yeah. There would be no more fighting for her for a while. She supposed an army of skeletons and a possessed Ice King was still a pretty good body count, but all her victories to get to this point felt suddenly hollow.

“…okay.”

“Good. That’s…that’s good.” He nodded, looking uncertain for a moment. Only for a moment, though. Then she saw the old, familiar resolve. “I’ll be back. I promise. Even if I’m…not myself anymore. I’ll be back.”

“You’d better.”

“And…Marcy? I’m sorry. For…”

“Don’t.” Marceline shook her head. If she let him apologize – for forgetting her, for forgetting himself, for leaving her, for not somehow overpowering the greatest evil in all of Ooo to keep it from using him to hurt her – she wouldn’t be able to stop from bawling like a little girl. Because he would just do the same thing all over again. He didn’t have a choice. And she wasn’t a little girl anymore.

“I forgive you,” she said instead. _I’ll forgive you for whatever you do, when you don’t remember me._ Then she forced herself to smile like her heart wasn’t breaking, and added: “But if I wake up to find out that the Lich has caused the extinction of all life…I’m gonna kick your butt.”

He laughed – not the Ice King’s maniacal, manic laugh, but Simon’s hesitant, almost shy chuckle. “Then I guess I’d better win. You’re way scarier than any Lich.”

Marceline laughed softly, feeling her cheeks growing warm. She ducked her head so her hair would hide it, and the tears now shining in her eyes. “You know it. Now, shoo.”

He nodded, taking a second to steel himself and his human nerves. Then he took to the air again, and turned away. She looked up to watch him go.

Only when the flapping of his beard was completely inaudible to her keen hearing did Marceline let out a long, tired sigh, letting out all the energy she’d been using just to stand upright. She finally let herself collapse to the floor.

“Werk?” asked Gunter, waddling over to peer down at her.

“Bring me an apple,” Marceline ordered tiredly. “Try not to bruise it.”

“Werk.” Gunter waddled off. She had no idea if it had understood her. She had no idea if he’d even remembered to keep something red around for when she visited. But it was worth a shot. She was starving, but she was too exhausted to do anything about it.

There and then, right there on the floor of the castle and shielded by the cold, Marceline turned onto her side, resting her head on her arms, and fell into a deep, dark sleep.

As she slept, Marceline remembered.

_“Marceline?”_

_She’d started to look forward to his visits, so the sound of his voice echoing in the cave outside no longer filled her with the dread it used to. There and then, however, Marceline froze in shock mid-strum, eyes going wide._

_Then she zoomed to the window in a flash, just to get a look outside so she could stop deluding herself. It would just be the Ice King out there. Even when he sometimes sort of sounded like Simon, it was just an echo. She’d been coming to terms with that._

_When she looked out the window, however, she didn’t see the Ice King. She saw Simon Petrikov, glasses and all. Without the crown._

_“Hey, little lady.”_

_Marceline all but tumbled out of the window, all of her usual inhuman grace gone in the face of what she was seeing. At first, all she could do was stammer and stare. Eventually, however, she found her voice._

_“…Simon?” She sounded like the little girl who had died a long time ago, after he’d left her._

_Simon nodded, and smiled at her. Even his teeth looked less like fangs. “That’s right. I…I’m okay now.” And he sounded happy. He sounded so happy. He sounded happy and relieved and_ himself _, and… “Thanks to you, Marcy.”_

_She hadn’t even questioned it, at the time. She’d just laughed, so happy that it had to bubble out of her. She’d hurried over to him. He’d even held out his arms to hug her._

_And then, over his shoulder, at the mouth of the cave, she’d seen Finn, limping, dragging an unconscious Jake behind him and holding his sword high in his other hand._

_“Marceline, don’t!” he’d screamed, his voice full of terror. “That’s not really Ice King! It’s not Simon!”_

_Sheer surprise made Marceline stumble to a stop. Sheer surprise saved her life. She stared at Finn, wide eyed, trying to process what she was seeing and what he’d said._

_Simon stepped forward, resting both hands on her shoulders in what was almost a gesture of comfort. But then his grip tightened, stronger than what he’d ever been capable of. Stronger even than Ice King._

_Marceline looked up in alarm, and found herself staring into two eyes that were black and empty as the void, but for two glowing green pinpricks._

_Simon smiled, and the expression stretched his face into something insane and frightening._

_“Aren’t you cold…Marcy?”_

Marceline woke up, flailing, and the first thing she did was swallow back a scream. For several seconds, she couldn’t remember anything – where she was, how she’d got there, what had happened before she’d fallen asleep. All she could think of was the blackness of the Lich’s eyes, like a shroud over her thoughts.

The red of a tomato, left beside her, stood out like a jewel against the ice all around her. Marceline grabbed at it with shaking hands and sank her fangs into it, gulping down the color until the fruit was as bleached white and colorless as nearly everything else in this kingdom seemed to be. It wasn’t much, but it took the edge off the hunger pains.

She remembered that she’d asked Gunter to bring her something, and from there, memories trickled back. Marceline looked around, realizing that she was still in Ice King’s castle. She wasn’t where she’d passed out – someone, maybe Ice King, maybe the Gunters, had moved her into an empty room.

She also realized that a noise she’d been picking up on the very edge of hearing was actually voices, far away but echoing through the castle hallways. The sheer presence of them probably meant that the Lich hadn’t succeeded, or at least hadn’t succeeded yet. Marceline let herself hope, and set off floating in search of the source.

As she drifted closer, she started to pick out individual voices. There was Finn, and Jake, and Bubblegum, and Ice King.

“Don’t play dumb, Ice King! We know you’re keeping Marceline here!”

“I am not playing dumb! Marceline is not a princess! And I only take princesses! It’s my thing. I can’t believe you’ve forgotten my thing!”

“Believe me, Ice King, we try to forget your thing on a daily basis.”

“Well, Marceline is my homey. My posse. No relation to a princess at all! There is a difference! Like the lack of kidnapping. So there’s no need to be jealous, Princess…”

“Ew! Don’t touch me! And tell us where you’re keeping her, or else!”

It sounded like same old, same old was going on around the corner. If not for how ragingly hungry she was, she might have thought she’d dreamed everything from before.

She knew she hadn’t, however. And so the promise of things being… _normal_ again actually made her smile slightly. If things were normal again, things were okay. Everyone was alive.

Everything else that was wrong, well…she would deal. And there was plenty of her to go around. She could definitely be in two posses at once.

Taking a deep breath, Marceline floated around the corner. The scene that met her eyes was just what she’d pictured – Finn, Jake, and Bubblegum menacing Ice King, who was menacing them right back while obviously having no idea what they were accusing him of. 

“Hi, guys,” she said, waving to get their attention. It worked – they all looked up, wide eyed and surprised. Marceline, in turn, felt her gaze swiveling as though on a winch to what Jake was lugging along in one stretched out, overlarge fist. It looked like a paint can. Judging by the stains on its metal surface, it looked like a red paint can. “Candy cane” red, if she was any judge. Her favorite.

Finn was the first to recover. “Marceline! Are you okay?”

“Sure,” she said, drifting over to Jake. “But I’d be a lot better if that was for me.” She pointed at the paint can. Jake obligingly levered up the lid, and Marceline sank to the ground and buried her face in the red, slurping with relish.

Apparently satisfied that she was in no immediate danger that some food couldn’t fix, Finn turned back to Ice King. “Aha! I knew you had her!”

“Yeah, uh…I guess I did.” Ice King sounded genuinely thrown. He moved over to Marceline and leaned down enough to whisper. “Marceline. What are you doing here?”

Marceline lifted her head just long enough to answer. “You said I could sleep over.”

“I did?”

“Yeah. Ask Gunter.”

“Oh.” She could almost hear the gears shifting in his head. Despite himself, despite all the evidence that he shouldn’t, Ice King trusted Gunter. If the penguin vouched for her, then clearly he’d told Marceline she could sleep over.

“Y-Yeah, of course!” he said, accepting this as truth. “I told Marceline she could sleep over. Because she was…”

“Tired,” said Marceline helpfully.

“Tired! And because Marceline is cool enough to hang out with me! Unlike you two losers!” He stuck his tongue out at Finn and Jake.

Marceline laughed. “Yeah,” she said, turning her head to wink at Finn and Jake so that Ice King couldn’t see. “Losers.” Then she stood up enough to give Ice King a shoulder bump. “Thanks for letting me hang out. I feel a lot better. I feel…awesome.”

He had no idea what she really meant by that. He probably had no real recollection of everything that had happened last night. She could see it just by looking at him.

But he gave her a shoulder bump back, and smiled. It wasn’t Simon’s smile, but it wasn’t the Lich’s smile either. “No problem. Anything for my good buddy Marceline. Um…you wanna keep staying over, maybe?”

“Sorry. I’ve gotta go. My latest house is still probably a wreck.”

“Oh.” He looked disappointed, and Marceline felt a pang on his behalf. He wasn’t Simon. But she was fast starting to learn that Ice King wasn’t so bad.

“Well, you know how it is,” she said, trying to cheer him up. “You can’t come over to visit if you’re already there.”

“I guess you can’t.” Then, his voice ringing with hesitant, hopeful optimism: “So…that means you’re going to come over and visit again, right?”

It was a question he asked her a lot, even though her answer was always the same. Marceline wasn’t sure if he kept asking because he forgot her answer, or because he just didn’t believe it. She gave it again anyway. “You know it. See you then. Come on, less cool guys.” She picked up the paint can with one hand and beckoned with the other. “Let’s go home.”

Jake graciously agreed to expand to a size big enough for Marceline to ride along, provided she ate over the side. Marceline agreed, although spillage wasn’t much of a problem. Sticking her face in and slurping, with the occasional pause to stir more of the red to the top, was all she wanted to do.

But by the time she’d sucked the Candy Cane Red paint to Pale Ivory, perfect for painting Bubblegum’s lab tables, they still had a ways to go. Marceline taught them a song to pass the time.

“It’s kind of short,” Finn said, when she was sure they all remembered it. “Maybe you should write a little more.”

“Maybe I will,” said Marceline thoughtfully, staring out at the landscapes passing below Jake’s feet. Between the three of them, they’d remembered to bring her sunhat along on the rescue. “I’ve just got to find the right beat to go with it. And the right lyricist to help me write it.”

Even if Ice King never remembered how he’d taught her that song, maybe he’d be up for putting a new spin on it.

Until then, the cheerful chorus marked their passage all the way home.

_“Dun da da da da dun dun!”_


End file.
